1. Field of the Invention
The present invention relates generally to the treatment of process streams and, more particularly, to catalytic wet oxidation systems and methods for treatment of undesirable constituents therein.
2. Description of Related Art
Wet oxidation is a well-known technology for treating process streams, and is widely used, for example, to destroy pollutants in wastewater. The method involves aqueous phase oxidation of undesirable constituents by an oxidizing agent, generally molecular oxygen from an oxygen-containing gas, at elevated temperatures and pressures. The process can convert organic contaminants to carbon dioxide, water and biodegradable short chain organic acids, such as acetic acid. Inorganic constituents including sulfides, mercaptides and cyanides can also be oxidized. As an alternative to incineration, wet oxidation may be used in a wide variety of applications to treat process streams for subsequent discharge, in-process recycle, or as a pretreatment step to supply a conventional biological treatment plant for polishing. Catalytic wet oxidation has emerged as an effective enhancement to traditional non-catalytic wet oxidation. Catalytic wet oxidation processes generally allow for greater destruction to be achieved at a lower temperature and pressure, and therefore a lower capital cost. An aqueous stream to be treated is mixed with an oxidizing agent and contacted with a catalyst at elevated temperatures and pressures. Heterogeneous catalysts typically reside on a bed over which the aqueous mixture is passed, or in the form of solid particulate which is blended with the aqueous mixture prior to oxidation. The catalyst may be filtered out of the oxidation effluent downstream of the wet oxidation unit for reuse.